1. Fields of the Invention
The present invention relates to a sprinkler, and more particularly, to a drive mechanism for a sprinkler.
2. Descriptions of Related Art
The conventional drive mechanism 9 for a sprinkler is disclosed in FIG. 8 and discloses a hollow shaft 91 to which an end support 92, a gear casing 93 and a hose (not shown) are connected. The whole assembly mentioned above is connected to a base. The end support 92 of the drive mechanism 9 has a hollow positioning rod 921 mounted to the hollow shaft 91. A gear set 922 is connected to one end of the hollow shaft 91 so as to be engaged with the output gear 931 of the gear casing 93. The other end of the positioning rod 921 has an end toothed portion 923 which is engaged with the toothed face 911 of the end support 92. A sleeve 94 and a spring 95 are respectively installed in the hollow positioning rod 921 to provide the gear casing 93 a force to be positioned, so that the sprinkler can stably and periodically spray water. The end support 92 is connected to the gear casing 93 by the hollow shaft 91, when the hydraulic force swings the gear casing 93 and the hose relative to the end support 92, the end toothed portion 923 of the hollow positioning rod 921 is cooperated with the horizontal compression force of the spring 95 to change the positions relative to the toothed face 911 of the end support 92. Therefore, the gear casing 93 and the hose quickly swing back and forth.
The spring 95 is a metal part which is to provide an axial force to support the sleeve 94 to prevent the collar 924 on the end support 92 from being loosened when the water hits the gear casing 93. Once the collar 924 is loosened, the gear casing 93 may not be able to swing.
However, because of the resilient nature of the spring 95, when the end support is connected to the gear casing 93, the hollow shaft 91 is difficult to be secured because of the force from the spring 95. Furthermore, the metal spring 95 increases the manufacturing cost.
The present invention intends to provide a drive mechanism for a sprinkler wherein the structure of the drive mechanism is simplified and no metal spring is required.